[contravariant]

You need the medium, gravity, and 'push' to get a wave. Calling them <medium>-wave, or 'push'-wave doesn't really tell you anything useful, so they're called gravity-waves. An alternative would have been buoyancy-wave, but apparently this didn't catch on (buoyancy and gravity are really two sides of the same coin, anyway).

[Godel_unicode]

Buoyancy is related to density, which is independent of gravity. Check: buoyancy can exist in a non-inertial reference frame provided acceleration in a "downward" direction.

Also, you don't need gravity to be the force being acted against in order to form a wave. You can get impact waves in water at 0g because of surface tension.

https://en.m.wikipedia.org/wiki/Buoyancy